(()=>{
    interface IPerson{
        firstName: string
        lastName: string 
    }

    class Person{
        firstName:string
        lastName:string
        fullName:string 

        constructor(firstName:string,lastName:string){
            this.firstName = firstName
            this.lastName=lastName

            this.fullName = this.fullName +'_' +this.lastName
        }
    }

    function showFullName(person:IPerson){
        return person.firstName+'_'+person.lastName
    }

    const person = new Person('wang','xiaohu')

    console.log(showFullName(person))
})()